Texture painting with flow, hardness, density
The patch still has yet to be reviewed properly after the suggestions Campbell made on initial review, and there are actions requested because the code system for paint affects several modes in the unified paint system. There are instructions on building blender to include patches in the build, but those instructions don't appear here on BSE - I see from a previous search that asking about how to build blender is off topic here. That said, I see from a google search that there are many options covering the different OS available.